Question: What is the planet Neptune's natural satellite?
Paraphrase: What is the planet Neptune's common satellite?
SPARQL (Wikidata):  select distinct ?obj where { wd:Q332 wdt:P398 ?obj . ?obj wdt:P31 wd:Q2537 } 
Answer: Hippocamp, moon of Neptune, Triton, Naiad, Nereid, Proteus, Thalassa, Despina, Galatea, Larissa